The present disclosure generally relates to devices for injecting medicinal substances, and more particularly relates to a medical fluid delivery device for subcutaneously administering viscous liquid medicines into the body of a user.
Subcutaneous infusion devices are well known in the medical arts for use in the administration of a selected medicinal substance to a desired infusion site located underneath the skin of a patient or user. Commonly included in such infusion device is a tubular cannula or catheter that is supported by and protrudes from a hub for receiving the medicinal substance via a delivery tubing. Typically, the hub includes a small needle that is inserted just under the surface of the skin, and remains in place for up to several days.
More specifically, such infusion devices provide an alternative to intravenous delivery of medicines and allow the medicinal substance to be administered through a layer of skin immediately below the dermis and epidermis. As is known in the art, such use of the subcutaneous infusion devices decreases the number of times the patient must have an injection to receive frequently administered medicines. Although not all medicines can be administered through such infusion devices, they are an effective and convenient way to administer medicinal substances without having to impose multiple injections on the patient.
However, some medicinal substances are highly viscous (i.e., in the range of 3-10 cP or centipoise) and are delivered at high flow rates, and conventional subcutaneous infusion devices are not designed to deliver the highly viscous substance at these flow rates. As a result, a build-up of excessive delivery pressure during the delivery of such substances is likely to occur, and clogging may occur in the needle or its adjacent areas during infusion. Further, because the needle used in the infusion device is typically bent about 90 degrees, the risk of kinking is relatively high at or near the bent portion of the needle.
Another issue of conventional infusion devices is that movement of the hub can cause the needle to break during use. Foldable gripping wings are typically attached to the hub for securely holding the needle when inserting the needle straight into the desired infusion site at a 90 degree angle relative to the skin surface. Specifically, the wings are folded back away from the needle and pinched together between two fingers. At times, the folded wings slide against each other during the insertion step, making the insertion of the needle rather challenging. Further, if the needle is made of a smaller diameter, the needle is not supported firmly and causes it to break during use.
Therefore, there is a need for improving subcutaneous infusion devices to facilitate a more stable retention of the needle on the skin during the insertion step, and for reducing flow resistance of highly viscous substance during the delivery step.